src/libstore: Print the reason opening the DB failed

Without this, the error is lost, and it makes for a hard to debug
situation. Also remove some of the busyness inside the sqlite_open_v2
args.

The errcode returned is not the extended one. The only way to make open
return an extended code, would be to add SQLITE_OPEN_EXRESCODE to the
flags. In the future it might be worth making this change,
which would also simplify the existing SQLiteError code.

1 files changed, 7 insertions, 3 deletions

diff --git a/src/libstore/sqlite.cc b/src/libstore/sqlite.cc
index 6c350888f..353dff9fa 100644
--- a/src/libstore/sqlite.cc
+++ b/src/libstore/sqlite.cc
@@ -47,9 +47,13 @@ SQLite::SQLite(const Path & path, bool create)
     // `unix-dotfile` is needed on NFS file systems and on Windows' Subsystem
     // for Linux (WSL) where useSQLiteWAL should be false by default.
     const char *vfs = settings.useSQLiteWAL ? 0 : "unix-dotfile";
-    if (sqlite3_open_v2(path.c_str(), &db,
-            SQLITE_OPEN_READWRITE | (create ? SQLITE_OPEN_CREATE : 0), vfs) != SQLITE_OK)
-        throw Error("cannot open SQLite database '%s'", path);
+    int flags = SQLITE_OPEN_READWRITE;
+    if (create) flags |= SQLITE_OPEN_CREATE;
+    int ret = sqlite3_open_v2(path.c_str(), &db, flags, vfs);
+    if (ret != SQLITE_OK) {
+        const char * err = sqlite3_errstr(ret);
+        throw Error("cannot open SQLite database '%s': %s", path, err);
+    }
 
     if (sqlite3_busy_timeout(db, 60 * 60 * 1000) != SQLITE_OK)
         SQLiteError::throw_(db, "setting timeout");